KCuTa3O9 Groult D, Hervieu M, Raveau B Journal of Solid State Chemistry 53 (1984) 184-192 A Pentagonal Tunnel Structure with Copper in Square Planar Coordination: The Oxides KCuNb3O9 and KCuTa3O9 _cod_database_code 1001197 _database_code_amcsd 0013527 8.862 10.187 7.638 90 90 90 Pnc2 atom x y z K1 .081 .259 .255 Cu1 .5 0 .252 Cu2 .5 0 .752 Ta1 .4292 .252 -.003 Ta2 .8021 .4360 -.018 Ta3 .7991 .0613 -.012 O1 0 0 0 O2 0 0 .5 O3 .260 .118 -.031 O4 .259 .403 .061 O5 .575 .384 .058 O6 .576 .392 .461 O7 .875 .253 .006 O8 .406 .186 .258 O9 .171 .589 .249 O10 .271 .540 .757